Location determination for individual tires of a multi-tire

ABSTRACT

An apparatus and a method are provided for ascertaining the relative position of a first tire and a second tire in a multiple tire. The apparatus may include a first electromechanical transducer providing a first sensor signal indicating a contact area length of the first tire in the multiple tire, and a second electromechanical transducer providing a second sensor signal indicating a contact area length of the second tire in the multiple tire. The apparatus includes a reception unit configured for receiving the first and second sensor signals; a contact area characteristic ascertainment unit ascertaining the contact area lengths characteristic of the first and second tires based on the first and second sensor signals; and a position finding unit ascertaining the position of the first tire relative to the second tire by evaluating the contact length characteristics of the first and second tires during cornering.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to an apparatus for ascertaining a relativeposition for individual tires in a multiple tire.

The invention also relates to a vehicle.

The invention also relates to a method for ascertaining a relativeposition for individual tires in a multiple tire.

Furthermore, the invention relates to a program element.

The invention also relates to a computer-readable storage medium.

Modern motor vehicles form complex systems of hardware and software. Theregulation and control of the mechatronic system of an automobileinvolves the use of a large number of very different controllers.Intelligent tire systems also integrate the contact area of a tire intothe operation of a motor vehicle.

The contact area of a tire denotes the tire footprint or a magnitudewhich is indicative of the tire footprint. Such a magnitude isparticularly the length of the contact area, that is to say the lengthmeasured in the direction of travel, along which the tire is in contactwith the road. During travel, the tire footprint on a passenger vehicleis frequently only approximately as large as the palm of a hand. On amotorcycle, it is even smaller. The contact area of a tire, to be moreprecise the contact area length, can be ascertained by using a piezoelement in the tire.

However, the control of a vehicle by vehicle electronics may alsorequire it to be possible to reliably distinguish sensor signals fromdifferent piezo elements in different tires from one another.

BRIEF SUMMARY OF THE INVENTION

The invention is based on the object of providing a tire system in whichsensor signals from different piezo elements in different tires can bedistinguished from one another with feasible complexity and reliably.

This object is achieved by the subject matter of the independent patentclaims. Advantageous embodiments of the present invention are describedin the dependent claims.

In accordance with a first aspect of the invention, an apparatus forascertaining a relative position for individual tires in a multiple tire(for example a twin tire) is provided, wherein the apparatus has areception unit which is set up to receive a first sensor signal from afirst electromechanical transducer (for example a first piezo element)associated with a first tire in the multiple tire, wherein the firstsensor signal is indicative of a contact area length for the first tire.The reception unit is also set up to receive a second sensor signal froma second electromechanical transducer (for example a second piezoelement) associated with a second tire in the multiple tire, wherein thesecond sensor signal is indicative of a contact area length for thesecond tire. The apparatus also contains a contact area characteristicascertainment unit which is set up to take the first sensor signal as abasis for ascertaining a contact area length characteristic(particularly an absolute or relative contact area length, moreparticularly a contact area length which is associated with a tirefootprint) for the first tire and to take the second sensor signal as abasis for ascertaining a contact area length characteristic for thesecond tire. A position finding unit is set up to ascertain the positionof the first tire in relation to the second tire in the multiple tire byevaluating the contact area length characteristic of the first tire andthe contact area length characteristic of the second tire, ascertainedwhile the vehicle is cornering.

In accordance with another exemplary embodiment of the invention, avehicle (for example a motor vehicle, particularly a passenger vehicleor a heavy goods vehicle) having an apparatus with the aforementionedfeatures for ascertaining a relative position for individual tires in amultiple tire is provided.

In accordance with a further exemplary embodiment of the invention, amethod for ascertaining a relative position for individual tires in themultiple tire is provided. The method involves a first sensor signalfrom a first electromechanical transducer associated with a first tirein the multiple tire being received, wherein the first sensor signal isindicative of a contact area length for the first tire. In addition, asecond sensor signal from a second electromechanical transducerassociated with a second tire in the multiple tire is received, whereinthe second sensor signal is indicative of a contact area length for thesecond tire. A contact area length characteristic for the first tire isascertained on the basis of the first sensor signal and a contact arealength characteristic for the second tire is ascertained on the basis ofthe second sensor signal. Furthermore, the position of the first tire inrelation to the second tire is ascertained by evaluating the contactarea length characteristic of the first tire and the contact area lengthcharacteristic of the second tire during cornering.

A computer-readable storage medium according to an exemplary embodimentof the present invention stores a program for ascertaining a relativeposition for individual tires in a multiple tire, which program is setup to perform or control the method having the features described abovewhen it is executed by a processor.

A program element (computer program element) according to an exemplaryembodiment of the present invention for ascertaining a relative positionfor individual tires in a multiple tire has the method steps describedabove (or controls said method steps or performs them) when it isexecuted.

Exemplary embodiments of the present invention can be implemented eitherby means of a computer program, that is to say a piece of software, orby means of one or more specific electric circuits, that is to say inhardware, or in arbitrary hybrid form, that is to say by means ofsoftware components and hardware components.

Within the context of this application, a “relative position” betweenindividual tires is understood to mean particularly a piece ofinformation which provides details about the relative arrangement of twotires with respect to one another on a vehicle. By way of example, saidinformation may contain the arrangement of a tire on the left or right,at the rear or front, and in the case of a multiple tire additionallythe information whether said tire is situated on the rear inside left oron the rear outside left, for example.

Within the context of this application, the term “multiple tire” isunderstood to mean particularly an arrangement of two or more tireswhich are mounted rigidly on one another and are provided directlyadjacently to one another, particularly a twin tire or a triplet tire.

Within the context of this invention, the various “units”, particularlythe reception unit, the contact area characteristic ascertainment unitand the position finding unit, may each be understood to mean aprocessor or a portion of a processor which performs the respectivefunctions of the relevant unit. Each unit may be in the form of aseparate processor, or a plurality of or all units may be in the form ofportions of a common processor.

Within the context of this application, the “contact area lengthcharacteristic” can be understood to mean a characteristic relating tothe tire footprint on a bed, such as a road. In this case, thecharacteristic of a contact area can denote the surface area or else thegeometry of the coverage of the contact area, for example thedescription of a rectangular or essentially trapezoidal contact areaconfiguration. This may indicate an absolute or preferably a relative(ascertainable with a high level of accuracy) measure of a contact arealength.

A “contact area length” can be understood to mean the length of asurface section of a tire which is in contact with a bed such as a road.

An “electromechanical transducer” can be understood, in particular, tomean a transducer which converts mechanical signals such as twists intoelectrical signals or vice versa. By way of example, anelectromechanical transducer element of this kind may be in the form ofa piezo element which is mounted on a tire such that it experiences acharacteristic sequence of twists upon each contact area pass when thetire is rotating.

In accordance with one exemplary embodiment of the invention, the factthat a contact area geometry and consequently a contact area lengthcharacteristic for twin tires are characteristically altered duringcornering in comparison with straight-ahead driving can be used toascertain a relative position between individual tires in the twin tireor electromechanical transducers associated with said tires. Thisprinciple can be generalized for triplet tires or generically N-plettires (N≧2). While a contact area geometry is essentially rectangularduring straight-ahead driving, the present inventors have discoveredthat in the case of twin tires or generically multiple tires theindividual tires are each distorted essentially trapezoidally. Thisdistortion has a different extent depending on whether the individualtire in such a multiple tire is situated on the inside of the curve oron the outside of the curve. On the basis of the resultingcharacteristic, which can be captured by sensors using a respectiveelectromechanical transducer element integrated in the tire, individualsensor signals can be associated with individual tires arranged atparticular positions. This may be advantageous from the point of view ofdesired tire-specific control, for example.

The text below describes additional refinements of the apparatus. Thesealso apply to the vehicle, to the method, to the program element and tothe computer-readable storage medium.

The position finding unit may be set up to ascertain the position byevaluating an—during cornering—at least essentially trapezoidaldistortion in the contact area of the first tire together with an—duringcornering—at least essentially trapezoidal distortion in the contactarea of the second tire. On the basis of the forces which act duringcornering, particularly centrifugal or centripetal forces, corneringresults in distortion of an otherwise at least essentially rectangulargeometry of a tire contact area. During cornering, the tires aredeformed from the rectangular contact area geometry to an ever greaterextent the further away a respective tire is from the center of thecurve. On the basis of the correlation between the respective contactarea deformations and the corresponding contact area lengths, contactarea length analysis allows the arrangement of the respective tire inrelation to the center of a curve to be ascertained and henceposition-based sorting of the different tires to be performed. Since themanner in which the contact area lengths during cornering change incomparison with the contact area lengths during straight-ahead drivingis dependent on the position of an electromechanical transducer on atire, the position of an electromechanical transducer of this kindshould be chosen properly. In many cases, it is expedient for anelectromechanical transducer of this kind to be arranged in the centerof a tire profile.

In accordance with one exemplary embodiment, the position finding unitmay be set up to ascertain, as the position of the first tire inrelation to the second tire, which of the first and second tires is theinner-curve tire and which of the first and second tires is theouter-curve tire. A reason for this distinguishability is the dependencyof the contact area behavior on centripetal and centrifugal forces.

In accordance with one exemplary embodiment of the invention, theposition finding unit may be set up to ascertain the position on thebasis of the premise or assumption that during cornering an at leastapproximately trapezoidal distortion in the contact area of a tire ismore pronounced for the outer-curve tire among the first and secondtires than for an inner-curve tire among the first and second tires.This may result in a different contact area length, with a lookup table,for example, being able to be used to store an empirical ortheoretically derived correlation between the change in the trapezoidaldistortion, the position in relation to a curve and an arrangement ofthe tire on a vehicle. When appropriate sensor signals have beencaptured, access to such a lookup table can then be used to associatethe tires with individual positions. The position finding unit may beset up to ascertain the relative position of the individual tires in themultiple tire by evaluating an alteration in the contact area length ofthe first tire together with an alteration in the contact area length ofthe second tire when changing between straight-ahead driving andcornering. The very behavior of a contact area length alteration whenchanging from straight-ahead driving to cornering or vice versa canprovide information about the relative position of the tire with a highlevel of precision. As an alternative to such measurement of contactarea length alterations, it is also possible to use an absolute valuefor a contact area length ascertained during cornering in order toderive the position information. In the case of yet another exemplaryembodiment, it is possible to use a ratio or a difference betweencontact area lengths of different tires in order to infer the position.

In accordance with one exemplary embodiment, the reception unit may beset up to receive a third sensor signal from a third electromechanicaltransducer associated with a third tire in another multiple tire,wherein the third sensor signal is indicative of a contact area lengthfor the third tire. The reception unit may also be set up to receive afourth sensor signal from a fourth electromechanical transducerassociated with a fourth tire in the other multiple tire. The fourthsensor signal may be indicative of a contact area length for the fourthtire. The contact area characteristic ascertainment unit may be set upto take the third sensor signal as a basis for ascertaining a contactarea length characteristic for the third tire and to take the fourthsensor signal as a basis for ascertaining a contact area lengthcharacteristic for the fourth tire. In addition, the position findingunit may be set up to ascertain the position of the third tire inrelation to the fourth tire while the other multiple tire is corneringby evaluating the contact area length characteristic of the third tiretogether with the contact area length characteristic of the fourth tire.In such a configuration, it is possible to sort two twin tires, forexample, on a common axle (front axle, rear axle) of a vehicle inrespect of the position by evaluating for all four (or more) tires the(absolute or relative) contact area length or the alteration thereinduring cornering and by associating the derived contact area lengthalteration characteristic with a position in relation to the curve.

In particular, the position finding unit may be set up to distinguishthe respective inner-curve tire in the multiple tire and in the othermultiple tire from the respective outer-curve tire in the multiple tireand in the other multiple tire by evaluating the contact area lengthcharacteristic of the first and second tires together with the contactarea length characteristic of the third and fourth tires duringcornering. The basis for this distinction may again be the differentcharacteristic of the behavior of the contact area geometry and hence ofthe contact area lengths of the individual tires on the basis of aposition for the respective tire relative to the center of a curve.

Referring to the exemplary embodiment described previously, the positionfinding unit may also advantageously be set up such that it identifiesthe respective inner-curve tire as that tire in the multiple tire and inthe other multiple tire whose contact area length is decreasing byevaluating the contact area length characteristic of the first andsecond tires together with the contact area length characteristic of thethird and fourth tires when changing from straight-ahead driving tocornering. The outer-curve tire can be identified as that tire in themultiple tire and in the other multiple tire whose contact area lengthis increasing. The information “increase or reduction in the contactarea length” can therefore be used to safely separate the differentmultiple tires from one another. Within the multiple tires, adistinction can be drawn between the respective individual tires on thebasis of the level to which such an increase or reduction is pronounced.

A respective instance of the electromechanical transducers can generatea sensor signal which is indicative of the contact area length in thecenter of the respective tire cross section. It has been found that whenan electromechanical transducer, for example a piezo element, isarranged in the center (based on an inner-curve edge and an outer-curveedge of the tire) of a tire cross section, the characteristic behaviorof said piezo element during cornering is particularly characteristic ofthe position of the tire.

The contact area characteristic ascertainment unit may be set up toascertain the respective contact area length characteristic on the basisof the respective sensor signal as a result of a twist in the respectiveelectromechanical transducer during a contact area pass by the tire. Ifan electromechanical transducer is in the form of a piezo element, saidtransducer is initially twisted from an untwisted position during acontact area pass, then transferred to an essentially untwisted stateand finally twisted again before the twist relaxes again. This resultsin a timing response for an electrical signal, the length of whichbetween two successive zero crossings is a measure of the contact arealength.

In accordance with one exemplary embodiment, the apparatus may be in theform of a tire module. In other words, the apparatus may be provided asa modular component which can be arranged integrally on or in a tireand, by way of example, forwards appropriate tire position informationto vehicle electronics. Alternatively, the apparatus may be at leastpartly in the form of a vehicle electronics module, that is to saydirectly part of the vehicle electronics.

The inventive distinguishability between individual tires in a twin tirecan be combined with one or more further distinctions which, by way ofexample, permit “front”/“rear” and “left”/“right” distinction. By way ofexample, the “front”/“rear” distinction can be made by virtue of thealteration in the contact area length during acceleration or brakingbehavior being examined. If a vehicle accelerates positively on astraight section, the contact area length for the front tires becomesshorter and the contact area length for the rear tires becomes longer.Hence, it is possible to associate the tires with axles. Alternatively,it is also possible for a radio transmitter (for example a low-frequencytransmitter, for example at 125 kHz) to transmit a signal which iscaptured by sensors on the individual tires. If the radio transmitter isfitted to the rear of a vehicle, the path difference up to the tiresresults in different detected amplitudes, which allows “front”/“rear”distinction. For the purpose of “left”/“right” distinction, it ispossible for acceleration sensors which are offset from one another byan angle (for example 90°) to be fitted to the tires and for the timingresponse of said acceleration sensors to be ascertained, for example.One of the two sensors lags the other in terms of timing response, whichlikewise allows association.

The text below describes additional refinements of the vehicle. Thesealso apply to the apparatus, to the method, to the program element andto the computer-readable storage medium.

By way of example, the vehicle may be an automobile (for example a motorvehicle, particularly a passenger vehicle or heavy goods vehicle).Alternatively, it is possible for the inventive tire position capturesystem to be implemented in a train or the like.

It is pointed out that embodiments of the invention have been describedwith reference to different inventive subject matter. In particular,some embodiments of the invention are described by means of apparatusclaims and other embodiments of the invention are described by means ofmethod claims. However, it will become immediately clear to a personskilled in the art upon reading this application that, unless explicitlystated otherwise, any combination of features which can be attributed todifferent types of inventive subject matter is also possible in additionto a combination of features which can be attributed to one type ofinventive subject matter.

Further advantages and features of the present invention arise from thefollowing exemplary description of currently preferred embodiments. Theindividual figures of the drawing in this application should beconsidered merely schematic and not to scale.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1A and FIG. 1B schematically show an apparatus for ascertaining arelative position for individual tires in a twin tire based on anexemplary embodiment of the invention.

FIG. 1C schematically shows a contact area pass by a tire and aprinciple for the ascertainment of a contact area length of the basis ofa sensor signal from an electromechanical transducer during such acontact area pass.

FIG. 2 shows a vehicle with twin tires during straight-ahead driving.

FIG. 3 shows a vehicle with twin tires during cornering.

DESCRIPTION OF THE INVENTION

Identical or similar components in the different figures have beenprovided with the same reference numerals.

In accordance with one exemplary embodiment of the invention, a systemis provided which allows the position of sensors in twin tires to beresolved essentially without additional technical complexity, that is tosay particularly to augment a piece of “rear left” information with theinformation “rear inside left” or “rear outside left”.

The problem can be addressed using technically complex methods, forexample LF (Low Frequency) trigger or field-strength measurements.Drawbacks of such systems are in each case a high level of equipmentcomplexity or a high level of application complexity and dependency ofthe sensitivity for different vehicle variants.

The basis for one exemplary embodiment of the invention is a tire systemwith the capability of measuring contact area lengths (that is to saythe length of the tire footprint on the road) for individual tires. Forindividual tires, the tire contact area is approximately rectangularwhen traveling without transverse or longitudinal acceleration. Duringcornering (transverse acceleration), the rectangular shape is distortedinto an approximately trapezoidal shape, with the longer side of thetrapezium coming to rest toward the outside of the curve. In the tiremodule of the system, a (piezo) sensor, for example, measures thecontact area length, for example approximately in the center of the tirecross section.

In accordance with the invention, the trapezoidal distortion of anindividual tire is advantageously used to locate individual tires in atwin tire. In this case, the effective tire contact area effectivelycomprises two contact area faces of the two individual tires. Thetrapezoidal distortion now occurs on both tire contact area faces and ismore pronounced overall on the contact area face of the outer-curve tirethan on the contact-area face of the inner-curve tire. During cornering,the sensors in the two outer-curve twins now measure increased contactarea lengths overall, and the two sensors in the inner-curve twinsmeasure decreased contact area values overall. However, use if now madeof the effect that within the two outer-curve twins the outer twin inthis case reports an even more seriously increased contact area value incomparison with the inner partner twin. The reason is the trapezoidaldistortion which extends over both twins which was addressed above.

In a six-wheel vehicle, for example, the problem arises of sorting thetwo identities of the “rear left” position according to inner/outer. Tothis end, the relative changes in the measured contact area lengths areanalyzed and a contact area measured value increasing or decreasing to acomparatively greater extent during cornering is associated with theouter twin, and the contact area value increasing or decreasing to acomparatively lesser extent is associated with the inner twin. Thisanalysis of measured values, which are transmitted anyway, inconjunction with available vehicle data allows the additionalinformation to be obtained without additional equipment complexity.

In some cases, the contact area lengths of the tires in absolute formhave only limited suitability for comparison with one another.Tolerances in the ascertainment of the absolute contact area lengthwould, in unfavorable cases, make quantitative comparison of contactarea lengths, which have been ascertained in different tires bydifferent sensors, difficult or even practically impossible. In such ascenario, it is then advantageous to base a comparison between thesignals on relative signals. To this end, the contact area length ofeach tire is ascertained for straight-ahead driving withoutacceleration/deceleration—that is to say in a static driving state—, asit were the basic contact area length. During a dynamic driving state(that is to say during a curve or when accelerating or braking), dynamiccontact area lengths are then measured and are related to the basiccontact area length. It is thus possible to ascertain a measure of thecontact area alteration during the dynamic driving state(extension/contraction). This measure of the alteration can now becompared among different tires. Component tolerances, systematicinaccuracies as a result of different assembly, etc. are cancelled outin the approach.

All of these driving-state-dependent functions also work with regularlymeasuring and transmitting sensors. Although the sensor itself has noknowledge of whether the vehicle is in a static driving state or in adynamic driving state, the transmissions by said sensor are processed bya receiver and onboard computer which can use the data network of thevehicle to assess the driving state very well (time stamp for reception,back-calculation for the measurement time on the basis of knowledge ofthe internal sensor processes (AD converter time, processing time,transmission time), retrospection for synchronous vehicle data, such astransverse longitudinal acceleration, engine torque, brake lights,steering wheel angle, etc.) and to evaluate the transmissions by thetire sensors differently in accordance with the driving state. As aresult, although the convergence time of the function at vehicle levelis sometimes extended somewhat, it is possible to use very simplesensors which are reduced to only the bare necessities and which do nothave to perform any complicated data (pre)processing.

One exemplary embodiment of the invention allows the ascertainmentresults to be used for tire pressure checking. In this connection, itmay be advantageous to be able to associate tire pressure sensors interms of the position thereof.

The text below describes an apparatus 100 for ascertaining a relativeposition for individual tires 102, 104 in a twin tire 110 based on anexemplary embodiment of the invention with reference to FIG. 1A and FIG.1B.

As FIG. 1B shows, the apparatus 100 is based on the first tire 102 beingequipped with a piezo element 114 at a tire center position 132.Accordingly, the second tire 104 is equipped with a second piezo element116 along a tire center position 134.

Using the example of the first tire 102, FIG. 1C shows how the flexuralstate of the piezo element 114 alters during a contact area pass, thatis to say a period between points 2 and 4 in FIG. 1C, when the tire isrotating in a direction 136 and hence a portion of the tire 102 isrespectively in contact with a bed 138, such as a road. Before the startof the contact area pass, position 1, the piezo element 114 is unflexed.At the start of the contact area pass, see position 2, the piezo element114 flexes, which results in an electrical signal. This is followed by astate 3, during which the piezo element 114 is unflexed again beforebeing flexed again at the end of the contact area pass, see position 4.This results in a time-dependent electrical signal from the piezoelement 114, for which a distance between two zero crossings is ameasure of the contact area length 140.

As FIG. 1A also shows, the electromechanical transducer elements 114 and116 of a reception unit 112 in the apparatus 100 transmit the respectivesensor signals. A first sensor signal from the first tire 102 in thetwin tire 110 is supplied to the first electromechanical transducer 114,so that the first sensor signal is indicative of a contact area lengthfor the first tire 102. The reception unit 112 also receives a secondsensor signal for the second tire 104 in the twin tire 110, which secondtire has the associated second electromechanical transducer 116. Thissecond sensor signal is indicative of a contact area length for thesecond tire 104.

The reception unit 112 supplies the signal, which can be preprocessed bysaid reception unit, for example, to a contact area characteristicascertainment unit 118. The latter is set up to take the first sensorsignal as a basis for ascertaining the contact area lengthcharacteristic of the first tire 102 and to take the second sensorsignal as a basis for ascertaining the contact area lengthcharacteristic of the second tire 104. In this case, the contact arealength can be ascertained directly, or it is advantageously possible fora parameter value which is indicative of the contact area length, forexample a relative value for the contact area length, to be ascertained.As has been described previously, the length of a signal between twozero crossings is characteristic of the respective contact area length.

The ascertained contact area length information is supplied to aposition finding unit 120 which ascertains the relative position of thefirst tire 102 in relation to the second tire 104 by evaluating thecontact area length characteristic of the first tire 102 and the contactarea length characteristic of the second tire 104. This is based on thefact that, during cornering, the contact area lengths of the tires 102,104 are altered in different ways, specifically on the basis of how therelative position of the respective tire, to be more precise therespective piezo element 114 or 116, is situated in relation to a curvecenter point.

As FIG. 1A also shows, a database 142 is provided which the units 112,118, 120 can access for the purpose of retrieving or storing data. Inaddition, the position finding unit 120 is coupled to an output unit 144which can be provided with the result of the position determination. Byway of example, the output unit 144 may be a vehicle electronics unitwhich can use the ascertained positions of the individual tires 102, 104for control purposes in the vehicle. It is also possible for the outputunit 144 to be a graphical user interface which a user can use to becomeinformed about the sensor values for the individual tires. It is alsopossible for the output unit 144 to initiate a measure directly, forexample an alarm, if values are found to be outside an additionaltolerance range.

FIG. 2 shows a schematic view 200 of a road 220 on which anautomobile—not shown in detail—is moving. Said automobile has a rearaxle 222 and a front axle 224 and, in FIG. 2, is moving in a straightline and currently without acceleration in a direction 226. On the rearaxle 222, the twin tire 110, which is formed from the directly adjacentindividual tires 102, 104, is positioned on the right in FIG. 2. Inaddition, another twin tire 206, formed from directly adjacent furthertires 202, 204, is positioned on the rear axle 222. The individual tires102, 104 in the twin tire 110 are mounted together and rigidly on oneanother, as are the individual tires 202, 204 in the other twin tire206. The two twin tires 110, 206 may either be suspended together on theaxle 222 or may be suspended individually and independently. A similarsituation applies to the further tires, which may be positioned alongthe front axle 224 and are not considered in more detail at thisjuncture.

As FIG. 2 shows, the contact area faces of the tires 102, 104, 202, 204are essentially rectangular, since straight-ahead driving withoutacceleration is involved.

FIG. 3 shows another scenario 300 during cornering, in which the road220 makes a curve. The vehicle is now moving in a cornering direction302. As FIG. 3 shows, this results in trapezoidal distortion of thecontact area faces of the tires 102, 104, 202, 204. Two individual tires102, 104 in a twin tire form approximately a common trapezium. Whenconsidered at high resolution, the two individual tires 102, 104 in thetwin tire may have a different trapezoidal distortion such that eachindividual tire 102, 104 experiences overlaid separate trapezoidaldistortion. The individual contact area faces exhibit trapezoidaldistortion which is different, however, which means that the measuredcontact area length of the individual tires is also being altered. Itshould be noted that the trapezoidal distortions shown in FIG. 3 aremerely schematic and not to scale. FIG. 3 shows that the behavior of thetires in an outer-curve region 310 differs from the behavior of thetires in an inner-curve region 320. The distortion is more pronounced onthe respective outer-curve tires 204, 104 than on the respectiveinner-curve tires 202, 102. In addition, the contact area lengths of thetwo outer-curve twins 204, 202 are increased, whereas those contact arealengths of the inner-curve twins 102, 104 are reduced.

The evaluation of the alteration in the respective contact area lengthsof the individual tires 202, 204 and 102, 104 allows explicitassociation of the individual sensor signals with the position of therespective tires 204, 202, 104, 102.

It is pointed out that the embodiments described here are merely alimited selection of possible variant embodiments of the invention. Itis thus possible for the features of individual embodiments to becombined with one another in a suitable manner, so that a person skilledin the art can regard the variant embodiments which are explicit here asdisclosing a large number of different embodiments in obvious fashion.

The invention claimed is:
 1. An apparatus for ascertaining a relativeposition of a first tire and a second tire in a multiple tire, theapparatus comprising: at least one processor and a non-transitorycomputer readable medium having a set of computer-readable instructionsstored thereon, which when executed by said at least one processor,causes said at least one processor to implement a plurality of unitsincluding: a reception unit configured for receiving a first sensorsignal indicating a contact area length of a first tire in a multipletire from a first electromechanical transducer associated with the firsttire, said reception unit configured for receiving a second sensorsignal indicating a contact area length of a second tire in the multipletire from a second electromechanical transducer associated with thesecond tire; a contact area characteristic ascertainment unitascertaining a contact area length characteristic of the first tirebased on the first sensor signal and ascertaining a contact area lengthcharacteristic of the second tire based on the second sensor signal; anda position finding unit ascertaining a position of the first tirerelative to the second tire in the multiple tire by evaluating thecontact length characteristic of the first tire and the contact arealength characteristic of the second tire during cornering.
 2. Theapparatus according to claim 1, wherein: the first tire has a contactarea and the second tire has a contact area; and said position findingunit ascertains the position of the first tire relative to the secondtire by evaluating a trapezoidal distortion in the contact area of thefirst tire during cornering and a trapezoidal distortion in the contactarea of the second tire during cornering.
 3. . The apparatus accordingto claim 1, wherein the position of the first tire relative to thesecond tire indicates which one of the first tire and the second tire isan inner-curve tire and which one of the first tire and the second tireis an outer-curve tire.
 4. The apparatus according to claim 1, wherein:the first tire has a contact area and the second tire has a contactarea; and said position finding unit ascertains the position of thefirst tire relative to the second tire based on a premise that, duringcornering, a trapezoidal distortion in the contact area of whichever oneof the first tire and the second tire is an outer-curve tire is morepronounced compared to whichever one of the first tire and the secondtire is an inner-curve tire.
 5. The apparatus according to claim 1,wherein said position finding unit ascertains the position of the firsttire relative to the second tire by comparing an alteration in thecontact area length of the first tire with an alteration in the contactarea length of the second tire when the multiple tire changes betweenstraight-ahead driving and cornering.
 6. The apparatus according toclaim 1, wherein: said reception unit receives a third sensor signalfrom a third electromechanical transducer associated with a third tirein another multiple tire, the third sensor signal indicates a contactarea length of the third tire; said reception unit receives a fourthsensor signal from a fourth electromechanical transducer associated witha fourth tire in the other multiple tire, the fourth sensor signalindicates a contact area length of the fourth tire; said contact areacharacteristic ascertainment unit ascertains a contact area lengthcharacteristic of the third tire based on the third sensor signal andascertaining a contact area length characteristic of the fourth tirebased on the fourth sensor signal; and said position finding unitascertains a position of the third tire relative to the fourth tire inthe multiple tire by evaluating the contact length characteristic of thethird tire and the contact area length characteristic of the fourth tireduring cornering.
 7. The apparatus according to claim 6, wherein: saidposition finding unit distinguishes an inner-curve tire from anouter-curve tire in the multiple tire by evaluating the contact arealength characteristic of the first tire and the contact area lengthcharacteristic of the second tire during cornering; and said positionfinding unit distinguishes an inner-curve tire from an outer-curve tirein the other multiple tire by evaluating the contact area lengthcharacteristic of the third tire and the contact area lengthcharacteristic of the fourth tire during cornering.
 8. The apparatusaccording to claim 6, wherein: said position finding unit distinguishesan inner-curve tire from an outer-curve tire in the multiple tire byevaluating the contact area length characteristic of the first tire andthe contact area length characteristic of the second tire, said positionfinding unit identifies the inner-curve tire in the multiple tire aswhichever tire in the multiple tire has the contact area length that isdecreasing when changing from straight-ahead driving to cornering, andsaid position finding unit identifies the outer-curve tire in themultiple tire as whichever tire in the multiple tire has the contactarea length that is increasing when changing from straight-ahead drivingto cornering; and said position finding unit distinguishes aninner-curve tire from an outer-curve tire in the other multiple tire byevaluating the contact area length characteristic of the third tire andthe contact area length characteristic of the fourth tire, said positionfinding unit identifies the inner-curve tire in the other multiple tireas whichever tire in the other multiple tire has the contact area lengththat is decreasing when changing from straight-ahead driving tocornering, and said position finding unit identifies the outer-curvetire in the other multiple tire as whichever tire in the other multipletire has the contact area length that is increasing when changing fromstraight-ahead driving to cornering.
 9. The apparatus according to claim1, wherein: the first tire has a cross sectional area with a center, andthe second tire has a cross sectional area with a center; the firstsensor signal generated by the first electromechanical transducerindicates the contact area length in the center of the cross sectionalarea of the first tire; and the second sensor signal generated by thesecond electromechanical transducer indicates the contact area length inthe center of the cross sectional area of the second tire.
 10. Theapparatus according to claim 1, wherein said contact area characteristicascertainment unit ascertains: the contact area length characteristic ofthe first tire based on a twist in the first electromechanicaltransducer during a contact area pass by the first tire; and the contactarea length characteristic of the second tire based on a twist in thesecond electromechanical transducer during a contact area pass by thesecond tire.
 11. The apparatus according to claim 1, in combination withthe multiple tire, wherein the multiple tire is a twin tire.
 12. Theapparatus according to claim 1, further comprising said firstelectromechanical transducer and said second electromechanicaltransducer.
 13. The apparatus according to claim 1, wherein saidreception unit, said contact area characteristic ascertainment unit, andsaid position finding unit form at least part of a tire module.
 14. Theapparatus according to claim 1, wherein said reception unit, saidcontact area characteristic ascertainment unit, and said positionfinding unit form at least part of a vehicle electronics module.
 15. Acombination, comprising: a vehicle; and the apparatus according to claim1, wherein the apparatus is included in the vehicle.
 16. A method forascertaining a relative position of a first tire and a second tire in amultiple tire, the method which comprises: with at least one processor,implementing at least a reception unit, a contact area characteristicascertainment unit, and a position finding unit; receiving, in thereception unit, a first sensor signal indicating a contact area lengthof a first tire in a multiple tire from a first electromechanicaltransducer associated with the first tire; receiving, in the receptionunit, a second sensor signal indicating a contact area length of asecond tire in the multiple tire from a second electromechanicaltransducer associated with the second tire; ascertaining, in the contactarea characteristic ascertainment unit, a contact area lengthcharacteristic of the first tire based on the first sensor signal;ascertaining, in the contact area characteristic ascertainment unit, acontact area length characteristic of the second tire based on thesecond sensor signal; and ascertaining, in the position finding unit, aposition of the first tire relative to the second tire in the multipletire by evaluating the contact length characteristic of the first tireand the contact length characteristic of the second tire duringcornering.
 17. A non-transitory computer-readable storage medium havinga set of computer-readable instructions stored thereon, which whenexecuted by at least one processor, causes the at least one processor toimplement a plurality of units including: a reception unit configuredfor receiving a first sensor signal indicating a contact area length ofa first tire in a multiple tire from a first electromechanicaltransducer associated with the first tire, said reception unitconfigured for receiving a second sensor signal indicating a contactarea length of a second tire in the multiple tire from a secondelectromechanical transducer associated with the second tire; a contactarea characteristic ascertainment unit ascertaining a contact arealength characteristic of the first tire based on the first sensor signaland ascertaining a contact area length characteristic of the second tirebased on the second sensor signal; and a position finding unitascertaining a position of the first tire relative to the second tire inthe multiple tire by evaluating the contact length characteristic of thefirst tire and the contact area length characteristic of the second tireduring cornering.